關於cannon.js我們已經學習了一些知識,今天郭先生就使用已學的cannon.js物理引擎的知識配合three基礎知識來做一個保齡球小遊戲,效果如下圖,線上案例請點選部落格原文。
我們需要掌握的技能點,就是已經學過的cannon.js物理引擎知識、three.js車削幾何體、threeBSP和簡單的shaderMaterial。下面我們來詳細的說一說如何製作這個遊戲。
1. 設計遊戲
因為我們已經使用過一些物理引擎,所以第一步我們很容易想到要用three做地面網格和牆面網格併為他們生成尺寸相當的剛體資料,這裡面要求牆面和地面固定不動,所以剛體質量設為0。然後就是瓶子,瓶子我們可以直接下載模型,但是為了複習之前的知識,我選擇使用車削幾何體配合著色器來完成。瓶子的剛體我們暫時使用柱體來模擬(雖然和瓶子網格不匹配,但是在物理引擎中其實很少使用外形匹配的剛體,一是因為和實際的效果相差並不大,二是因為簡單剛體的計算相對簡單),車削幾何體所需要的點我們可以通過畫圖或者ps來算出,讓。但是cannon.js的Cylinder預設的up方向和three.js的CylinderGeometry的up方向是不同的,這裡要注意。然後就是關於保齡球的設計思路,玩過保齡球的都知道,保齡球上面是有三個洞的(方便手指拿球),我們考慮使用ThreeBSP來繪製網格,相應的剛體我們使用球體即可。關於相機的控制,我們不使用控制器,在投球之前我們使用左右鍵來控制相機的左右移動,投球后我們讓相機跟隨球運動,在球發生相撞時,我們固定相機的位置。球的出射方向我們仍然使用滑鼠指標控制(使用螢幕座標轉三維座標),最後使用GUi來重置遊戲即可,差不多就是這個思路,下面我們來看程式碼。
2. 遊戲程式碼
程式碼比較簡潔,有必要的我們在程式碼中標註。
1. 初始化剛體
initCannon() { //初始化物理世界 world = new CANNON.World(); world.gravity.set(0, -9.8, 0); world.broadphase = new CANNON.NaiveBroadphase(); world.solver.iterations = 10; //初始化地面剛體 let groundBody = new CANNON.Body({ mass: 0, shape: new CANNON.Box(new CANNON.Vec3(groundSize.x / 2, groundSize.y / 2, groundSize.z / 2)), position: new CANNON.Vec3(0, -groundSize.y / 2, 0), material: new CANNON.Material({friction: 1, restitution: 0}) }) world.addBody(groundBody); //初始化牆面剛體 let wallLeftBody = new CANNON.Body({ mass: 0, shape: new CANNON.Box(new CANNON.Vec3(wallSize.x / 2, wallSize.y / 2, wallSize.z / 2)), position: new CANNON.Vec3(-(wallSize.x + groundSize.x) / 2, wallSize.y / 2, 0), material: new CANNON.Material({friction: 0, restitution: 0}) }) world.addBody(wallLeftBody); let wallRightBody = new CANNON.Body({ mass: 0, shape: new CANNON.Box(new CANNON.Vec3(wallSize.x / 2, wallSize.y / 2, wallSize.z / 2)), position: new CANNON.Vec3((wallSize.x + groundSize.x) / 2, wallSize.y / 2, 0), material: new CANNON.Material({friction: 0, restitution: 0}) }) world.addBody(wallRightBody); //初始化保齡球剛體 sphereBody = new CANNON.Body({ mass: 50, shape: new CANNON.Sphere(sphereRadius), position: new CANNON.Vec3(0, sphereRadius, 400), material: new CANNON.Material({friction: 0.2, restitution: 0}) }) world.addBody(sphereBody); //初始化瓶子剛體 for(let i=0; i<pingPositionArray.length; i++) { let pingBody = new CANNON.Body({ mass: 1, shape: new CANNON.Cylinder(2.5,2.5,20,18), quaternion: new CANNON.Quaternion().setFromEuler(Math.PI / 2, 0, 0),//因為柱體的up方向和three的up方向相差90度,這裡我們先旋轉90度讓圓柱體“站起來”。 position: new CANNON.Vec3(pingPositionArray[i][0],pingPositionArray[i][1],pingPositionArray[i][2]), material: new CANNON.Material({friction: 0.01, restitution: 1}) }) pingBodies.push(pingBody);//將瓶子剛體新增到剛體陣列中,這樣更容易計算 world.addBody(pingBody); } },
2. 初始化three.js
initThree() { //建立地面 this.initGround(); //建立牆體 this.initWall(); //建立瓶子 並引用 let pingMesh = this.createPing(); //pingPositionArray是瓶子位置陣列 for(let i=0; i<pingPositionArray.length; i++) { let pingMeshCopy = pingMesh.clone(); pingMeshCopy.position.set(pingPositionArray[i][0],pingPositionArray[i][1],pingPositionArray[i][2]); pingMeshes.push(pingMeshCopy); scene.add(pingMeshCopy); } //建立保齡球並引用 sphereMesh = this.createSphere(); sphereMesh.position.set(0, sphereRadius, 400); sphereMesh.rotation.set(Math.PI / 6, 0, - Math.PI / 12); scene.add(sphereMesh); }, createPing() { let points = []; //latheArray是瓶子車削幾何體所需點的陣列 for(let i=0; i<latheArray.length; i++) { points.push(new THREE.Vector2(latheArray[i][0]/10, latheArray[i][1]/10)) } let geometry = new THREE.LatheGeometry(points, 30); geometry.computeVertexNormals(); //著色器材質 let material = new THREE.ShaderMaterial({ vertexShader: ` varying vec3 vPosition; varying vec3 vNormal; void main() { vNormal = normal; vPosition = position; gl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 ); } `, fragmentShader: ` varying vec3 vPosition; varying vec3 vNormal; void main() { //光線向量 vec3 light = vec3(10.0, 10.0, 10.0); float strength = dot(light, vNormal) / length(light); float y = vPosition.y; //在 [3.1, 3.7]和[4.2, 4.8]之間被渲染成紅色並根據光線向量和法向量模擬光照 if(y < 4.8 && y > 4.2 || y < 3.7 && y > 3.1) { gl_FragColor=vec4(1.0, 0.4 * pow(strength, 2.0), 0.4 * pow(strength, 2.0), 1.0); } else { gl_FragColor=vec4( 0.6 + 0.4 * pow(strength, 2.0), 0.6 + 0.4 * pow(strength, 2.0), 0.6 + 0.4 * pow(strength, 2.0), 1.0); } } `, side: THREE.DoubleSide }); let mesh = new THREE.Mesh(geometry, material); mesh.quaternion.copy(new THREE.Quaternion().setFromEuler(new THREE.Euler(-Math.PI / 2, 0, 0))); //這裡將柱體網格新增到group中,為的是group的旋轉 let group = new THREE.Group(); group.add(mesh); return group; }, createSphere() { let material = new THREE.MeshPhongMaterial({color: 0xEE100F, shininess: 60, specular: 0x2C85E1, side: THREE.DoubleSide}); let sphereGeometry = new THREE.SphereGeometry(sphereRadius, 40, 24); let cylinderGeometry = new THREE.CylinderGeometry(sphereRadius/10,sphereRadius/10,sphereRadius,30); let sphereMesh = new THREE.Mesh(sphereGeometry, material); let cMesh1 = new THREE.Mesh(cylinderGeometry, material); let cMesh2 = cMesh1.clone(); let cMesh3 = cMesh1.clone(); cMesh1.position.set(1.14, sphereRadius, 0.67); cMesh2.position.set(-1.14, sphereRadius, 0.67); cMesh3.position.set(0, sphereRadius, -1.33); //構造BSP let bsp1 = new ThreeBSP(sphereMesh); let bsp2 = new ThreeBSP(cMesh1); let bsp3 = new ThreeBSP(cMesh2); let bsp4 = new ThreeBSP(cMesh3); //用球形幾何體,減去三個小的圓柱體 let resultBsp = bsp1.subtract(bsp2).subtract(bsp3).subtract(bsp4); let resultGeom = resultBsp.toGeometry();//這裡我們只需要匯出幾何體 resultGeom.mergeVertices();//注意這兩步,不然保齡球不會計演算法向量,也就不會平滑著色 resultGeom.computeVertexNormals(); return new THREE.Mesh(resultGeom, material); }, initGround() { let texture = new THREE.TextureLoader().load('/static/images/base/ground.jpg'); texture.wrapS = texture.wrapT = THREE.RepeatWrapping; texture.repeat.set(1, 4); let geometry = new THREE.BoxBufferGeometry(groundSize.x, groundSize.y, groundSize.z); let material = new THREE.MeshPhongMaterial({map: texture}); let mesh = new THREE.Mesh(geometry, material); mesh.position.y = -groundSize.y / 2; scene.add(mesh); }, initWall() { let material = new THREE.MeshLambertMaterial({color: 0x77dddd}); let geometry = new THREE.BoxBufferGeometry(wallSize.x, wallSize.y, wallSize.z); let leftMesh = new THREE.Mesh(geometry, material); let rightMesh = leftMesh.clone(); leftMesh.position.set(-(wallSize.x + groundSize.x) / 2, wallSize.y / 2, 0); rightMesh.position.set((wallSize.x + groundSize.x) / 2, wallSize.y / 2, 0); scene.add(leftMesh); scene.add(rightMesh); },
3. 定義事件
這裡我們需要滑鼠mousemove事件和onkeydown,onkeyup事件
document.onkeydown = this.handler; document.onkeyup = this.handler; this.$refs.box.addEventListener('mousemove', event => { //滑鼠移動,螢幕二維向量轉三維向量 let x = (event.clientX / window.innerWidth) * 2 - 1; let y = - (event.clientY / window.innerHeight) * 2 + 1; direction = new THREE.Vector3(x,y,-1).applyQuaternion(camera.getWorldQuaternion(new THREE.Quaternion())).normalize(); }) handler(event) { var down = (event.type == 'keydown'); switch(event.keyCode){ case 32: { if(down && time > event.timeStamp) { time = event.timeStamp;//time預設值為Infinity,第一次按下空格,給time賦值 } else if(down) { relaxation = event.timeStamp - time;//持續按下,計算累積時間 } else { //根據持續時間給球初始化速度 let t = relaxation > 5000 ? 500 : relaxation / 10; sphereBody.velocity.set(direction.x * t, direction.y * t, direction.z * t); sphereBody.angularVelocity.set(-1,0,0); time = Infinity; } } break; case 37: camera.position.x --; sphereBody.position.x --; break; case 39: camera.position.x ++; sphereBody.position.x ++; break; } },
主要程式碼大致就是這樣,下一節還會繼續cannon.js的學習。
轉載請註明地址:郭先生的部落格